1. Field of the Invention
The present invention relates, in general, to data processing systems.
2. Description of the Related Art
Data processing systems are systems that manipulate, process, and store data. Personal computer systems, and their associated subsystems, constitute well known examples of data processing systems.
One particularly popular type of personal computer system is the portable computer system (e.g., laptop, notebook, sub-notebook, and palm-held computer systems). Portable computer systems allow stand-alone computing and typically have their own power supplies, modems, and storage devices.
In order to allow maximum flexibility of use, portable computer systems typically have at least one rechargeable battery. A rechargeable battery is a device whose one or more cells(a cell is a device that converts a store of chemical energy into electrical energy) can be substantially reenergized once the store of chemical energy in the rechargeable battery has been partially or completely depleted. The at least one rechargeable battery generally serves as an internal power supply which allows the portable computer system to be powered up and used even when no external power supplies are present.
All things being relatively equal, the length of time during which a rechargeable battery can effectively power a portable data processing system depends upon the amount of electrical charge stored in the battery. Rechargeable batteries store energy in the form of like electric charges forced into a defined physical volume (often called a charge reservoir). The electrical charges are generally forced into the volume via use of a "battery charger." A battery charger is essentially a "charge pump" which uses power, typically supplied by a an external power supply such as a wall socket, to draw electric charges from a first volume and force the drawn electric charges into a second volume.
Insofar as like charges repel each other and unlike charges attract each other (e.g., a negative charge repels a negative charge and attracts a positive charge, while a positive charge repels a positive charge and attracts a negative charge), circuitry (e.g., portable computer system circuitry) can be electrically connected between the first and second volumes and potential energy associated with the stored charge converted to usable power as the stored charges in the second volume migrate back toward the first volume. For example, a battery charger might first draw positive charges from a negative charge reservoir (or first volume) of a rechargeable battery and force those positive charges into the positive charge reservoir (or second volume) of the rechargeable battery. Thereafter, personal computer power terminals can be electrically connected between the positive and negative terminals of the battery and the potential energy utilized as the positive electric charges in the second (positive terminal) volume migrate, in the form of an electric current, back toward the first (negative terminal) volume. (Those having skill in the art will recognize that it is generally the negative charges that so migrate, but that it is conventional to refer to the positive charges migrating.)
There is an upper physical limit on how much charge can be pumped into a given charge reservoir of a battery (e.g., a charge reservoir internal to a battery, where the charge reservoir is connected to a positive terminal of the battery) without damaging the battery. Once this physical limit has been reached, there is no practicable way of increasing the charge stored in the battery without adding additional physical volume to accept additional charges.
In light of the foregoing, it would seem that if additional battery capacity is desired for some reason (e.g., so that a data processing system can be powered a longer amount of time) it would be a relatively straightforward task to increase battery charge storage capacity (and hence battery life) merely by increasing the physical volume of the battery charge reservoirs in order to accommodate more charge. Unfortunately, such a straightforward operation is not practicable in the modern rechargeable battery environment for at least two reasons: modern rechargeable batteries are mass produced in standard shapes and sizes (i.e., with standard "form factors"), and hence batteries made in custom shapes and sizes (i.e., with custom "form factors") are prohibitively expensive; furthermore, data processing systems wherein rechargeable batteries are generally deployed tend to use smart battery technology.
Modern rechargeable batteries are produced in conformance with form factors. A form factor is a specification of a physical size and shape of a device. Batteries are generally mass-produced in accord with certain industry-wide form factors, and such batteries are generally inexpensive. If a custom form factor for a battery is desired, battery manufacturers generally will produce such custom form factor batteries, but such batteries tend to be far more expensive than the mass produced standard form factor batteries. Given the extreme price pressure in the personal computer environment, such custom form factor batteries are not a practicable option.
Those skilled in the art will also recognize that one way to increase battery capacity is to electrically connect (e.g., in electrical series or parallel) several batteries to get greater aggregate power. Unfortunately, this solution is not practicable due to modern data processing systems' reliance on smart battery technology.
Smart battery technology is a type of technology by which batteries are provided with built-in computational circuitry which informs a data processing system as to a wide range of information about the battery (e.g., charge in the battery, remaining battery life, battery voltage, etc.). An example of smart battery technology appears in the System Management Bus Specification Revision 1.0, Feb. 15, 1995, Copyright.COPYRGT. 1996, and System Management Bus Specification Revision 1.1, Dec. 11, 1998, Copyright.COPYRGT. 1996, 1997, 1998, standard which are hereby incorporated by reference in their entireties.
Smart batteries are designed to interface with a data processing system through the data processing system's smart battery bus (SMBUS), and because of this there is generally no easy way to increase battery capacity by connecting the batteries in series or parallel as with non-smart batteries. In addition, insofar as most data processing systems are designed to communicate with only one smart battery, there is no practicable way within the art of electrically connecting multiple smart batteries to a data processing system's SMBUS in such a way that will not confuse the data processing system, in that the data processing system is expecting to communicate with only one smart battery.
Even with the foregoing noted difficulties (custom form factor batteries not desirable/data processing system only expecting to communicate with one smart battery) associated with increasing battery capacity over and above that associated with one smart battery, there is a relatively constant need in the art for increased battery capacity (and hence increased battery life). In light of the foregoing discussion, it is apparent that a need exists in the art for a method and system capable of providing increased battery capacity without either (a) requiring the use of custom form factor batteries, or (b) unduly impacting the way in which existing data processing systems make use of smart battery technology.